To the Editor:— Mouth-to-mouth resuscitation is the preferred method of assisting ventilation in the emergency situation and is being taught to many lay groups such as lifeguards and firemen. However, there are complications attendant with the use of the technique, particularly by the less experienced. Complications include partial or total airway obstruction resulting in air being vented via the esophagus into the stomach when the operator exhales forcibly, and active or passive regurgitation of the victim's stomach contents into the upper airway. Since the report of Sellick, 1 many anesthesiologists have used posterior displacement of the cricoid cartilage to prevent active or passive regurgitation during the induction of anesthesia prior to insertion of an endotracheal tube in the patient with a full stomach. The cricoid cartilage is signet-ring shaped with the large flat plate just anterior to the esophagus. By applying posterior pressure to the skin over the anterior surface